As known, in the above-mentioned plants, the packaging units need to traverse a plurality of treatment or handling steps performed by respective treatment or handling stations prior to the delivery of the pourable product stored in the packaging units themselves to store houses. Examples of treatment or handling steps are the transformation of precursors of the packaging units to their final forms, the sanitization, the filling, the closing, the labeling and the grouping of the packaging units.
Furthermore, the processing speeds and the respective velocities with which the packaging units need to be conveyed may vary from one station to the other and the possible differences in conveying velocities need to be compensated during the transport of the packaging units. Additionally, an irregular supply of packaging units may arise due to e.g. the rejection of one or more defective packaging units.
A transfer device adapted to compensate for differences in processing speeds of different treatment stations is disclosed in WO2013185957. The transfer device is adapted to convey packaging units, in particular cardboard elements, along a rectilinear transport path from a receiving position to a delivery position. The transfer device comprises a circulating carrier and a plurality of first and second conveying elements arranged in alternation on the circulating carrier and supported by the same. The circulating carrier presents a rectilinear operative branch, a rectilinear return branch parallel to the operative branch and two curved branches configured to connect the operative branch and the return branch with each other.
Furthermore, the circulating carrier comprises a plurality of coil elements and each of the first and second conveying elements comprises magnetic elements adapted to selectively cooperate with the coil elements so as to advance the first and second conveying elements independently of each other along a path defined by the circulating carrier itself. Moreover, each first conveying element and one respective neighboring second conveying element are adapted to advance in cooperation one respective packaging unit along the rectilinear transport path defined by the operative branch.
An essentially similar transport device e.g. adapted to compensate for an irregular supply of packaging units is disclosed in WO2013189656. In this case, the packaging units are defined by pouches.
The transfer devices disclosed in WO2013185957 and WO2013189656 are construed to advance packaging units solely along rectilinear transport paths. The advancement of packaging units along curved branches is in fact subjected to geometrical limitations; the cooperation of one first and one second conveying element transporting therebetween one respective packaging unit along a transport path is difficult to be realized and depends on the angle of the curved branches with respect to the adjacent rectilinear branches.
A further transfer device as disclosed in EP2511203 is adapted to advance packaging units from a receiving position to a delivery position through a first and a second conveyor cooperating to one another.
The first and second conveyor comprise respectively a first horizontal circulating carrier and a horizontal second circulating carrier arranged side by side and each presenting a respective rectilinear operative branch, a respective return branch parallel to the respective operative branch and two respective curved branches for connecting the respective operative and return branches. Furthermore, the transfer device comprises a support unit, which is disposed between the operative branches of the first and second circulating carrier and on which the packaging units rest when advanced by the first and second conveyor.
More specifically, the first conveyor comprises a plurality of first conveying elements adapted to advance along a first path defined by the first circulating carrier, and the second conveyor comprises a plurality of second conveying elements configured to advance along a second path defined by the second circulating carrier. Each first conveying element and each second conveying element can be selectively controlled in speed and position. The operative branches of the first and second path are parallel to one another.
Furthermore, each first conveying element and one respective second conveying element are adapted to advance in cooperation a respective packaging unit, resting on the support unit, along a rectilinear transfer path, which is interposed between the operative branches of the first and second circulating carrier and is parallel to both.
Even in this case, the transfer device of EP2511203 is only configured to advance respective packaging units along a rectilinear transfer path.
Plus, the transfer device occupies significant space due to the location of the first and second conveyor on the opposite sides of the transfer path.
Furthermore, operation of the transfer device relies on the support unit coming along with additional parts, increased costs and additional control issues.